Black Unit Rollers Stained

[Bob Peterson]

I'm going to put this out here as the problem has me stumped. A sheetfed, oil based ink, print shop is indicating that the rollers in the black units are stained/glazed with a blue cast. The problem doesn't show up immediately, only at the end of the week when the ink is removed, and the press is finally washed up. None of the other colors/units exhibit the issue, and the stain is not creating any type of print problem. However, the blue cast/glaze is very difficult to remove.

They have tried different black inks, completely scrubbed /de-glazed the rollers, changed press wash, and even replaced rollers.

Has anyone experienced this issue, if so, how did you remedy it?

Thanks in advance!

 

[white rabbit]

Most black inks have blue in them to make the black denser in color. The blue dye is what you are seeing i think. I have this with my Magenta unit being pink. Bottchers Feboclean left on the rollers over the weekend (after washup) seems to do a good job of removing everything. Wash it up Monday morning and u should be good.

 

[Disappointed]

Sounds like calcification, basically dried fount water on the rollers. As said, Feboclean used to work and there are other de-calcifying products around too. Do you run an R/O or D/I unit for the water supply or straight tap water?

 

[D Ink Man]

It is the alkali blue pigment or even perhaps milori blue that is used in process blacks to make a good, dense, jet and BLUE black. Pigment 61 Red Shade is the most likely culprit.

I have actually encountered this in my past travels and it is due to a chemical interation between the alkali blue and usually the fountain solution. There is also a chance it is being caused by another one of the chemical consumables, interacting negatively, that are run on the press.

So the question is, 'how do I eliminate the problem'?

You have 2 choices.

1) Have the inkmaker formulate a black ink with no fugitive pigments like alkali blue or milori. A combination of carbazole violet and phthalo blue r/s does an excellent job to provide blue toning value in a process black. Another added benefit of the combo, is NO CHANCE for any pigment burn out due to the amines in aqueous and ultraviolet coatings. This change will cause an increase in the material cost of the ink. If you as an inkmaker explain it to the lithographer, exactly as I have outlined it, they should have no problem in paying the extra selling price that will be incurred from the material change.

2) You can experiment with changing the other consumables on press. One thing not mentioned was the press wash. Here is an easy experiment a printer can do in their shop to try to determine the chemical culprit.
Print BLACK ONLY on a coated stock with screen values of 10-20-30-.......up to 100% solid. You only need to run about 25 sheets. Let the form dry down completely, I would say at least 5 days, because today's inks are mostly stay open, and do take that amount of time to truly DRY. Now your ready. Take an eye dropper of all your consumables used on press. Using isopropyl alcohol, apply the various liquids and solutions to the print. Look for ANY bleed whatsoever of the ink films. After you have done this, you can narrow down what is causing the blue to stain your rollers. Fountain solution preppared, raw eth, raw sub, press wash, pre press chemicals used in the plate making process are some of the consumables that should be tested on the black prints.

This is a problem that can definitely be uncovered, discovered and remedied. Just listen to me, because I am the...

D Ink Man

 

[Asures]

Bob,

Just curious, what kind of press are they on?

Are they using processless plates that might be running plate emulsions up the roller train? On a Heidelberg or a Roland, the staining might not be as visible but on a press with any kind of copper rollers, the riders will certainly demonstrate more visual discoloration.

Are you sure that all rollers are touching to proper pressures within the unit? If they aren't and they wash up, obvoiusly there would be debris left over in the units causing discoloration / staining. Everyone looks at stripes of the Water Form and Ink form but without physically evaluating intermediates, that could lie a problem.

I've seen that countless times.

Instead of a Feebo Clean or Roller Paste, I'd probably be more inclined to use a Prisco Eezy Scrub or a Varn Take It Off which has a good slug of solvent in a paste / cream form with mild abrasives.

Good luck.

 

[D Ink Man]

Bob,

Just curious, what kind of press are they on?

Are they using processless plates that might be running plate emulsions up the roller train? On a Heidelberg or a Roland, the staining might not be as visible but on a press with any kind of copper rollers, the riders will certainly demonstrate more visual discoloration.

Are you sure that all rollers are touching to proper pressures within the unit? If they aren't and they wash up, obvoiusly there would be debris left over in the units causing discoloration / staining. Everyone looks at stipes of the Water Form and Ink form but without physically evaluating intermediates, that could lie a problem.

I've seen that countless times.

Instead of a Feebo Clean or Roller Paste, I'd probably be more inclined to use a Prisco Eezy Scrub or a Varn Take It Off which has a good slug of solvent in a paste / cream form with mild abrasives.

Good luck.

Read my post sir.

If you do what I say, you will need no "CLEAN".

Everything will be NATURALLY CLEAN.

A good man from GANS should know that.

You know, "The Best Ink in Cans".

Respectfully,
D

 

[Asures]

D -

Great contribution to the thread.

Did you pick those techniques up at Capitol, Flint, K&M, Braden, or at Sicpa =)?

Drinks on me when you're next in Los Angeles - good catch.

 

[D Ink Man]

Asures,

"Capico"

Then taught Flint and K&M. Braden Sutphin was unteachable.

At SICPA, I'm learning new techniques but am still teaching and offering what I have learned through experience.

Truly loving it! Thank you.

D

 

[Green Printer]

Braden Sutphin was unteachable.



D

You got that right. I second it. All in favor say I.

 

[Alois Senefelder]

Craving!!

Craving!!

Hello fellow Lithographers,

New rollers/blankets crave ink vehicles/solvents

The method I used to reduce this problem also the staing issue, was to Prime the new rollers/blankets

with a liquid ink reducer/solvent, this reduces the craving.

A film of liquid ink reducer/solvent is applied to the rollers/blanket and left for 15/30 minutes, then wiped off.


Regards, Alois

 

[Ajax]

Wait, you replaced rollers because of this? This is a typical problem with a lot of dense blacks but good lord to replace the rollers?! What I wouldn't give for a new roller set. Put some febo in there and tell your pressman to get over it.